Møller Peder C F, Mewis Jan, Bonn Daniel
Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24 Rue Lhomond, F-75231, Paris cedex 05.
Departement C.I.T., K.U. Leuven de Croylaan 46, B-3001, Leuven, Belgium.
Soft Matter. 2006 Mar 16;2(4):274-283. doi: 10.1039/b517840a.
The yield stress of many yield stress fluids has turned out to be difficult to determine experimentally. This has led to various discussions in the literature about those experimental difficulties, and the usefulness and pertinence of the concept of yield stress fluids. We argue here that most of the difficulties disappear when taking the thixotropy of yield stress fluids into account, and will demonstrate an experimental protocol that allows reproducible data to be obtained for the critical stress necessary for flow of these fluids. As a bonus, we will show that the interplay of yield stress and thixotropy allows one to account for the ubiquitous shear localization observed in these materials. However, due to the thixotropy the yield stress is no longer a material property, since it depends on the (shear) history of the sample.
事实证明，许多屈服应力流体的屈服应力很难通过实验确定。这引发了文献中关于这些实验困难以及屈服应力流体概念的实用性和相关性的各种讨论。我们在此认为，当考虑到屈服应力流体的触变性时，大多数困难就会消失，并将展示一种实验方案，该方案能够获得这些流体流动所需临界应力的可重复数据。此外，我们将表明，屈服应力和触变性的相互作用能够解释在这些材料中普遍观察到的剪切局部化现象。然而，由于触变性，屈服应力不再是一种材料属性，因为它取决于样品的（剪切）历史。
